Means of introducing an analyte into liquid sampling atmospheric pressure glow discharge
Inventors
Marcus, R. Kenneth • Quarles, JR., Charles Derrick • Russo, Richard E. • Koppenaal, David W. • Barinaga, Charles J. • Carado, Anthony J.
Assignees
Pacific Northwest National Laboratory • Clemson University • University of California San Diego UCSD
Publication Number
US-9536725-B2
Publication Date
2017-01-03
Expiration Date
2034-02-04
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Abstract
A liquid sampling, atmospheric pressure, glow discharge (LS-APGD) device as well as systems that incorporate the device and methods for using the device and systems are described. The LS-APGD includes a hollow capillary for delivering an electrolyte solution to a glow discharge space. The device also includes a counter electrode in the form of a second hollow capillary that can deliver the analyte into the glow discharge space. A voltage across the electrolyte solution and the counter electrode creates the microplasma within the glow discharge space that interacts with the analyte to move it to a higher energy state (vaporization, excitation, and/or ionization of the analyte).
Core Innovation
The invention describes a liquid sampling, atmospheric pressure, glow discharge (LS-APGD) device designed to generate a microplasma for vaporization, excitation, and/or ionization of an analyte. The device includes a first hollow capillary that delivers an electrolyte solution to a glow discharge space, and a second hollow capillary that serves as a counter electrode and delivers an aerosol containing the analyte into the glow discharge space. A voltage applied between the electrolyte solution and the counter electrode establishes the glow discharge microplasma, which interacts with the analyte to raise its energy state.
The LS-APGD device addresses the need for a secondary source of vaporization, excitation, and/or ionization complementary in size to small sample masses, such as those produced by laser ablation, offering lower operational costs, smaller footprint, and lower energy consumption compared to conventional inductively coupled plasma (ICP) sources which are large, gas- and power-intensive. This device enables efficient handling of analyte samples in small volumes, including nano-sized particles from femtosecond laser ablation, and provides a platform for compact elemental analysis systems.
The device contrasts with prior art LS-APGD arrangements that introduced the analyte within the electrolyte solution by delivering the analyte aerosol separately through a second hollow capillary into the glow discharge space. This design allows direct introduction of aerosol particulates into the microplasma, facilitating improved energy transfer and analysis. The system may additionally incorporate a laser ablation device to generate the aerosol analyte and an analysis instrument such as a monochromator or mass spectrometer to evaluate the excited or ionized analyte species produced by the microplasma.
Claims Coverage
The patent contains one independent claim that outlines a LS-APGD device with specific structural and functional features.
A LS-APGD device with dual hollow tubes delivering electrolyte solution and analyte aerosol
The device comprises a first hollow tube delivering a liquid electrolyte solution and a second hollow tube delivering an aerosol containing an analyte. Both tubes have inside diameters ranging from about 0.1 mm to about 2 mm and are arranged so that the flows exiting their discharge ends intersect within a glow discharge space.
Counter electrode formed by the second hollow tube terminal portion
A counter electrode is disposed at a distance of about 0.1 mm to about 5 mm from the first hollow tube's discharge end, with the terminal portion of the second hollow tube serving as this counter electrode.
Power source establishing voltage difference across discharge ends
A power source is in electrical communication with the conductive element of the first hollow tube and the counter electrode of the second hollow tube to establish a voltage difference across the distance, sustaining a glow discharge within the glow discharge space.
The independent claim collectively defines a LS-APGD device characterized by the spatial arrangement and functionality of two hollow tubes conveying electrolyte and analyte aerosol respectively, with a power source creating a glow discharge microplasma between the electrodes formed by these components.
Stated Advantages
Small footprint and low power consumption compatible with small sample volumes such as laser ablation aerosols.
Reduced gas and sample consumption resulting in no liquid waste.
Design simplicity facilitating easy integration with laser ablation devices and analytical instruments.
Capability to analyze nano-sized particles (less than about 10 nanometers) generated from femtosecond laser ablation.
Efficient vaporization, excitation, and ionization of analytes at atmospheric pressure microplasma.
Documented Applications
Use in elemental and isotopic mass spectrometry analysis of aerosols containing micro- and nano-particles, particularly from laser ablation sampling.
Integration with laser ablation devices for direct solid sample sampling and introduction to spectroscopic analysis.
Coupling with optical spectrometers including monochromators and polychromators to analyze excited state species from the glow discharge.
Analysis of aerosols produced by femtosecond and nanosecond pulsed lasers for depth profiling and quantitative elemental analysis.
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